Electric motors typically include a housing, a stator, and a rotor assembly. The housing includes a shell and two end shields and houses at least a portion of the rotor assembly. The rotor assembly includes a rotor core and a rotor shaft extending through the core. Some motor types and configurations include components to modify the motor operating characteristics for particular applications. Examples of such motor types are resistance start, reactor start, capacitor start, permanent split capacitor, and capacitor start-capacitor run motors. These different types of motors are characterized by different speed-torque characteristics and may be designed to provide different theoretical maximum efficiencies. For some applications, particularly those where high starting torque is required as in compressor motors, part of the windings in the motor serve as auxiliary or starting windings which are energized during initial excitation of the motor, but which are deenergized as the motor comes up to a predetermined speed. Deenergization of such windings is often accomplished by a centrifugal switch, or other appropriate device.
Electrical components used in some motor configurations include, in addition to the centrifugal switch, at least one capacitor and an overload. These components can be mounted to one of the motor end shields to facilitate access thereto. To provide protection from moisture, dust, and other contaminants, such components are often mounted in a closed "control compartment" in which the subject electrical components are housed.
Compressor motors typically used in today's consumer markets have moved to a direct drive construction. A direct drive construction compressor motor utilizes an end shield on the normal drive end of the motor to structurally support the compressor. The end shield typically includes a flange that accepts the cylinder sleeve, piston, crank, and head that are the basic components of the compressor. This direct integration of the compressor to the motor requires the rotor shaft to withstand unusually high side loading resulting from the compression stroke. Known electric motors that drive compressors typically utilize a stepped shaft configuration to limit shaft deflection and prevent crank bearing failures. Stepped shafts are expensive to manufacture due, at least in part, to the complexity of the shaft.
Accordingly, it would be desirable to provide a capacitor start-capacitor run motor with an inexpensive to fabricate rotor shaft that is capable of handling unusually high side loading. It would also be desirable to have all electronic components of the electric motor enclosed and protected from the external environment. It would further be desirable to provide easy access to at least some of the electrical components mounted to the motor.